Exposure to household pets from birth could reduce a child’s risk for allergies and obesity.

A study conducted by researchers from the University of Alberta looked at infant gut microbiota to see whether pre- or postnatal pet exposure would have a significant effect. The results were published in the April 2017 issue of Microbiome.

Researchers used a large subsample of 746 infants from the Canadian Healthy Infant Longitudinal Development Study (CHILD) cohort, whose mothers were enrolled during pregnancy. The mothers were given questionnaires and the infants were split into four categories based on exposure: no pet exposure in the pre- or postnatal periods; only prenatal pet exposure; both pre- and postnatal pet exposure; and only postnatal pet exposure. Because such a small number of infants fell into the category of only postnatal pet exposure—seven out of the total—that category was excluded from the final analysis.

More than half the infants had some exposure to pets—8% were exposed in pregnancy alone and 46.8% had exposure during both time periods.

To control for other factors, comparisons were conducted for specific groups with or without siblings, non-exclusively breastfed infants, as well as non-exclusively breastfed infants without siblings.

Pre- and postnatal pet exposure enriched the abundance of Oscillospira and/or Ruminococcus. Both bacteria are a little tricky to pin down in terms of benefits to infant health. Oscillospira has been detected in rRNA gene surveys of the human microbiome and been associated with “with leanness or lower body mass index in both infants and adults.” As for the role of ruminococcin, they are fiber degraders and typically predominant in formula-fed infants. In a previous study, researchers “observed a strong link between low levels of Ruminococcaceae and food sensitization at age 1, even after adjustment for major microbiota-disrupting events.” This suggests that infants with high levels of Oscillospira and Ruminococcus would be at a lower risk for allergies and obesity.

Some of the benefits of pet exposure applied to infants who had prenatal exposure but not postnatal exposure, indicating that the microbiome exchange could take place before birth. The researchers concluded that further research is needed to link the microbiota changes with the health outcomes of infants in this study as well as children in other cohorts.